Epidemiological Situation on Tick-Borne Spotted Fever Group Rickettsioses in the Russian Federation in 2012–2021, Prognosis for 2022–2026

The aim of the review was to characterize the epidemiological situation on rickettsiosis of the tick-borne spotted fever (TSF) group in the constituent entities of the Russian Federation in 2012–2021 and provide a long-term forecast for 2022–2026. In 2020–2021, indicators of registered incidence of tick-borne rickettsiosis in Russia on the whole decreased relative to the average long-term pre-pandemic level in 2012–2019 by 2 fold for all forms of the TSF group on average (Siberian tick-borne typhus – STT, Astrakhan spotted fever and Mediterranean fever). A comparative analysis of the territories revealed a correlation between the incidence of STT and the number of medical facility visits due to “tick bites” (r=0.67, p=0.015), which, against the background of an increase in the frequency of contacts of the population with vectors in 2020–2021 in most regions and a decrease in the incidence in the same regions indicates the credible nature of the changes. The ranking of territories according to average long-term incidence rates made it possible to classify the Republic of Altai and the Altai Territory as regions of extremely high epidemic hazard as regards STT; high hazard – the Republic of Tuva; above average – the Republic of Khakassia, Khabarovsk Territory and the Jewish Autonomous Region. The established downward trend in the incidence of tick-borne rickettsiosis among the population will be sustained in most entities of the Russian Federation within the next 5 years, excluding the Republic of Altai, the Altai Territory, the Republic of Crimea and the city of Sevastopol, where current incidence or an increase should be expected. The results of the analysis indicate the need to put more emphasis on natural-focal infections at the time of COVID-19 pandemic

Review of Epidemiological Situation on Rickettsioses in the Russian Federation in 2022 as Compared with 2013–2021, Forecast for 2023

The aim of the review was to characterize the epidemiological situation on tick-borne rickettsioses (TR) in the Russian Federation in 2022 in comparison with the pandemic years of 2020–2021 and the pre-pandemic period of 2013–2019, to give the forecast for 2023. During 2013–2022, a pattern was observed in the incidence of rickettsiosis of the tick-borne spotted fever group (with the exception of Astrakhan spotted fever – ASF), that is also characteristic of most other natural focal infections (NFIs): a sharp decrease in registered incidence rates in 2020–2021 with the subsequent increase in 2022 almost up to pre-pandemic levels or even exceedance in some regions. The absence of a defining influence of the frequency of contacts of the population with vectors on the decrease in the incidence in the period of 2020–2021 and the rise in the value in 2022 confirms the registration-related nature of the changes. Given due attention to the problem of effective detection and reporting of NFIs, we expect the incidence of tick-borne rickettsioses to remain within the confidence intervals of long-term average values in most endemic regions in 2023. Relaxed vigilance to the problem of NFIs may lead to a decline in the reported incidence of Siberian tick-borne typhus in the Krasnoyarsk and Zabaikalsky Territories, Republics of Tuva and Khakassia, Novosibirsk and Amur Regions; reduction in the incidence of ASF in Astrakhan Region. The main issue in detecting and registration of the tick-borne rickettsiosis incidence, objective assessment and forecasting of the epidemic situation as regards this group of infections is conditioned by the lack of domestic certified diagnostic test kits for laboratory verification of rickettsioses. Close cooperation between epidemiologists and clinicians is required to establish and register cases of TR based on clinical and epidemiological data

Application of Molecular Typing Methods for Analysis of Strains of Rickettsiae of the Spotted Fever Group and Rabies Virus

50 strains of spotted fever group (SFG) rickettsiae and 36 lyssaviruses strains from the collection of Omsk Research Institute of Natural Focus Infections were identified and typed using the approaches of molecular biology, epidemiology and bioinformatics. The taxonomic status of the studied cultures of SFG rickettsiae was identified. Zonation of the Russian Federation territories according to the spread of SFG pathogenic rickettsiae in their hosts - ixodic ticks was carried out. Lyssaviruses distribution in the territory of Siberia was considered

THE PRESENT STATE OF THE PROBLEM OF RICKETTSIOSES IN RUSSIA AND NEW APPROACHES TO THE CLASSIFICATION OF DISEASES CAUSED BY SPOTTED FEVER GROUP RICKETTSIAE

The paper presents analysis of the development and the current status of the doctrine about rickettsia and rickettsiosis. Progress in the study of Rickettsia is associated with, improved methods for their detection and isolation - using live biotechnological systems (cultivation in the experimental lines of ticks-sensitive lines of eukaryotic cells) in combination with methods of genotyping and. classical ricketsial methods. The development and. use of new methodological approaches to the study of tick-borne rickettsiae and other alpha-proteobacteria led to an important revision of ideas about genetic diversity, heterogeneity of antigenic and. biological characteristics, ecology and. contribution to the infectious pathology of various representatives of the order Rickettsiales in Russia

Features of the cultivation of a new genotype of Candidatus Rickettsia tarasevichae in biological models (cell culture, guinea pigs)

This paper presents the results of a study of some phenotypic properties (cultivation in biological models) of a new genotype Candidatus Rickettsia tarasevichae. The experiment was carried out in the eukaryotic cell culture Vero and guinea pigs. For the first time strains of Candidatus Rickettsia tarasevichae were isolated using cell culture. The benign experimental infection (with a primary lesion of cerebral vessels) was reproduced in guinea pigs.В работе представлены результаты изучения некоторых фенотипических свойств (культивирование на биологических моделях) нового генотипа Candidatus Rickettsia tarasevichae. Эксперимент был проведен на эукариотической культуре клеток Vero и морских свинках. Используя культуру клеток, впервые в мире удалось изолировать штаммы Candidatus Rickettsia tarasevichae. На морских свинках была воспроизведена доброкачественная экспериментальная инфекция с преимущественным поражением сосудов головного мозга

Dissemination of Spotted Fever Rickettsia Agents in Europe by Migrating Birds

Migratory birds are known to play a role as long-distance vectors for many microorganisms. To investigate whether this is true of rickettsial agents as well, we characterized tick infestation and gathered ticks from 13,260 migratory passerine birds in Sweden. A total of 1127 Ixodes spp. ticks were removed from these birds and the extracted DNA from 957 of them was available for analyses. The DNA was assayed for detection of Rickettsia spp. using real-time PCR, followed by DNA sequencing for species identification. Rickettsia spp. organisms were detected in 108 (11.3%) of the ticks. Rickettsia helvetica, a spotted fever rickettsia associated with human infections, was predominant among the PCR-positive samples. In 9 (0.8%) of the ticks, the partial sequences of 17kDa and ompB genes showed the greatest similarity to Rickettsia monacensis, an etiologic agent of Mediterranean spotted fever-like illness, previously described in southern Europe as well as to the Rickettsia sp.IrITA3 strain. For 15 (1.4%) of the ticks, the 17kDa, ompB, gltA and ompA genes showed the greatest similarity to Rickettsia sp. strain Davousti, Rickettsia japonica and Rickettsia heilongjiangensis, all closely phylogenetically related, the former previously found in Amblyomma tholloni ticks in Africa and previously not detected in Ixodes spp. ticks. The infestation prevalence of ticks infected with rickettsial organisms was four times higher among ground foraging birds than among other bird species, but the two groups were equally competent in transmitting Rickettsia species. The birds did not seem to serve as reservoir hosts for Rickettsia spp., but in one case it seems likely that the bird was rickettsiemic and that the ticks had acquired the bacteria from the blood of the bird. In conclusion, migratory passerine birds host epidemiologically important vector ticks and Rickettsia species and contribute to the geographic distribution of spotted fever rickettsial agents and their diseases

Dermacentor reticulatus: a vector on the rise

Dermacentor reticulatus is a hard tick species with extraordinary biological features. It has a high reproduction rate, a rapid developmental cycle, and is also able to overcome years of unfavourable conditions. Dermacentor reticulatus can survive under water for several months and is cold-hardy even compared to other tick species. It has a wide host range: over 60 different wild and domesticated hosts are known for the three active developmental stages. Its high adaptiveness gives an edge to this tick species as shown by new data on the emergence and establishment of D. reticulatus populations throughout Europe. The tick has been the research focus of a growing number of scientists, physicians and veterinarians. Within the Web of Science database, more than a fifth of the over 700 items published on this species between 1897 and 2015 appeared in the last three years (2013–2015). Here we attempt to synthesize current knowledge on the systematics, ecology, geographical distribution and recent spread of the species and to highlight the great spectrum of possible veterinary and public health threats it poses. Canine babesiosis caused by Babesia canis is a severe leading canine vector-borne disease in many endemic areas. Although less frequently than Ixodes ricinus, D. reticulatus adults bite humans and transmit several Rickettsia spp., Omsk haemorrhagic fever virus or Tick-borne encephalitis virus. We have not solely collected and reviewed the latest and fundamental scientific papers available in primary databases but also widened our scope to books, theses, conference papers and specialists colleagues’ experience where needed. Besides the dominant literature available in English, we also tried to access scientific literature in German, Russian and eastern European languages as well. We hope to inspire future research projects that are necessary to understand the basic life-cycle and ecology of this vector in order to understand and prevent disease threats. We conclude that although great strides have been made in our knowledge of the eco-epidemiology of this species, several gaps still need to be filled with basic research, targeting possible reservoir and vector roles and the key factors resulting in the observed geographical spread of D. reticulatus. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-016-1599-x) contains supplementary material, which is available to authorized users